Feedback reduction schemes for coordinated transmission

Abstract

Some of the embodiments of the present disclosure provide a method for reducing interference feedback in a mobile device operating in a wireless system employing coordinated transmission. The method comprises the mobile device establishing a plurality of channels with a plurality of base stations. The plurality of base stations includes a serving base station and one or more interfering base stations. The method further comprises the mobile device reporting, to the serving base station, reduced feedback information including a vector approximation of a feedback matrix associated with an interfering channel established with an interfering base station. Other embodiments are also described and claimed.

What is claimed is: 
     
       1. A method for reducing interference feedback in a mobile device operating in a wireless system employing coordinated transmission, the method comprising:
 the mobile device establishing a plurality of channels with a corresponding plurality of base stations, wherein the plurality of base stations include (i) serving base station and (ii) a plurality of interfering base stations; 
 the mobile device selecting a subset of the plurality of interfering base stations, wherein the subset of the plurality of interfering base stations excludes at least a first interfering base station of the plurality of interfering base stations; and 
 the mobile device reporting, to the serving base station, (i) feedback information associated with the serving base station and (ii) feedback information associated with each interfering base station of the subset of the plurality of interfering base stations, wherein the mobile device refrains from reporting, to the serving base station, feedback information associated with the first interfering base station. 
 
     
     
       2. The method of  claim 1 , wherein the subset of plurality of interfering base stations comprises a second interfering base station of the plurality of interfering base stations, and wherein reporting feedback information associated with each interfering base station of the subset of the plurality of interfering base stations comprises:
 the mobile device reporting, to the serving base station, feedback information including a vector approximation of a feedback matrix associated with an interfering channel established with the second interfering base station of the subset of plurality of interfering base stations. 
 
     
     
       3. The method of  claim 1 , wherein the subset of the plurality of interfering base stations comprises two interfering base stations of the plurality of interfering base stations. 
     
     
       4. The method of  claim 1 , wherein selecting the subset of the plurality of interfering base stations further comprises:
 selecting the subset of the plurality of interfering base stations such that the subset of the plurality of interfering base stations have higher levels of interference among the plurality of interfering base stations. 
 
     
     
       5. The method of  claim 1 , wherein selecting the subset of the plurality of interfering base stations comprises:
 the mobile device selecting the subset of the plurality of interfering base stations such that the subset of the plurality of interfering base stations comprises a second base station of the plurality of interfering base stations, wherein interference signals received from the second base station include a strongest one of a plurality of interfering signals correspondingly received by a plurality of antennae of the mobile device. 
 
     
     
       6. The method of  claim 1 , wherein:
 the subset of the plurality of interfering base stations comprises a second base station of the plurality of interfering base stations; and 
 the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations comprises Eigen vector approximation of interference signal received from the second base station of the plurality of interfering base stations. 
 
     
     
       7. The method of  claim 1 , wherein reporting the feedback information associated with the serving base station further comprises:
 reporting an Eigen vector approximation of a strongest one of a plurality of serving signals correspondingly received by a plurality of antennae of the mobile device from the serving base station. 
 
     
     
       8. The method of  claim 1 , further comprising:
 prior to reporting the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations, whitening the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations, 
 wherein whitening the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations comprises 
 estimating a covariance of thermal noise and interference from interfering base stations outside a reporting set of the plurality of interfering base stations. 
 
     
     
       9. The method of  claim 1 , wherein the feedback information associated with the serving base station comprises:
 two vector approximations of a feedback matrix associated with a channel established with the serving base station. 
 
     
     
       10. The method of  claim 9 , wherein the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations comprises Eigen vector approximations associated with each interfering base station of the subset of the plurality of interfering base stations. 
     
     
       11. An apparatus, comprising:
 one or more antennae; 
 a channel establishment module configured to establish a plurality of channels via the one or more antennae with a corresponding plurality of base stations, wherein the plurality of base stations includes Lla serving base station and (ii) a plurality of interfering base stations; and 
 a feedback reporting module configured to
 select a subset of the plurality of interfering base stations, wherein the subset of the plurality of interfering base stations excludes at least a first interfering base station of the plurality of interfering base stations, and 
 report to the serving base station, via the one or more antennae, (i) feedback information associated with the serving base station and (ii) feedback information associated with each interfering base station of the subset of the plurality of interfering base stations, wherein the apparatus refrains from reporting, to the serving base station, feedback information associated with the first interfering base station. 
 
 
     
     
       12. The apparatus of  claim 11 , wherein:
 the subset of the plurality of interfering base stations comprises a second interfering base station of plurality of interfering base stations; and 
 the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations comprises a vector approximation of a feedback matrix associated with an interfering channel established with the second interfering base station of the subset of plurality of interfering base stations. 
 
     
     
       13. The apparatus of  claim 11 , wherein the subset of the plurality of interfering base stations comprises two interfering base stations of the plurality of interfering base stations. 
     
     
       14. The apparatus of  claim 11 , wherein the feedback reporting module is further configured to select the subset of the plurality of interfering base stations such that the subset of the plurality of interfering base stations have higher levels of interference among the plurality of interfering base stations. 
     
     
       15. The apparatus of  claim 11 , wherein the feedback reporting module is further configured to select the subset of the plurality of interfering base stations by:
 selecting the subset of the plurality of interfering base stations such that the subset of the plurality of interfering base stations comprises a second base station of the plurality of interfering base stations, wherein interference signals received from the second base station include-a strongest one of a plurality of interfering signals correspondingly received by a plurality of antennae of the apparatus. 
 
     
     
       16. The apparatus of  claim 11 , wherein:
 the subset of the plurality of interfering base stations comprises a second base station of the plurality of interfering base stations; and 
 the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations comprises an Eigen vector approximation of an interference signal received from the second base station of the plurality of interfering base stations. 
 
     
     
       17. The apparatus of  claim 11 , wherein the feedback information associated with the serving base station comprises:
 an Eigen vector approximation of a strongest one of a plurality of serving signals correspondingly received by a plurality of antennae of the apparatus from the serving base station. 
 
     
     
       18. The apparatus of  claim 11 , further comprising:
 a whitening module configured to, prior to the reporting of the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations, whiten the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations, 
 wherein the whitening module is further configured to whiten the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations by
 estimating a covariance of thermal noise and interference from interfering base stations outside a reporting set of the plurality of interfering base stations. 
 
 
     
     
       19. The apparatus of  claim 11 , wherein the feedback information associated with the serving base station comprises:
 two vector approximations of a feedback matrix associated with a channel established with the serving base station. 
 
     
     
       20. The apparatus of  claim 19 , wherein the feedback information associated with each interfering base station of the subset of the plurality of interfering base stations comprises Eigen vector approximations associated with each interfering base station of the subset of the plurality of interfering base stations.